Aster family (Asteraceae)
Description: This biennial or short-lived perennial plant is up to 2½' and unbranched, except near the inflorescence. The central stem is slightly ridged and has scattered white hairs. The alternate leaves are up to 3½" long and 1½" across. These leaves clasp the stem, and become smaller and fewer as they ascend toward the inflorescence. They are usually lanceolate or broadly lanceolate, but sometimes oblanceolate, obovate, or broadly ovate. The margins may be smooth, or there may be a few scattered teeth toward the tips of the leaves.
At the apex of the central stem, as well as from some of the axils of the upper leaves, there is a single stalked inflorescence that branches into about 3-15 daisy-like composite flowers. Each composite flower is about ½¾" across, and consists of numerous yellow disk florets and 100-300 surrounding white ray florets. Sometimes, the ray florets are slightly pink or purple. There is little or no floral scent. The blooming period occurs from late spring to early summer, and lasts about 1½ months. Afterwards, this plant tends to die down during hot, dry summer weather. The root system is shallow and fibrous, and may form a short caudex in older plants. The achenes have white tufts of hair, which are carried aloft by the wind, thereby distributing the plant. Colonies are often formed.
Cultivation: The preference is full or partial sun, and moist conditions. Drier locations may be tolerated, depending on the local ecotype of the plant. Growth is best in fertile, loamy soil, but gravel and clay are tolerated in moist areas as well. Foliar disease doesn't bother this plant significantly as it tends to die down before disease organisms have a chance to develop.
Range & Habitat: Philadelphia Fleabane is a common plant that occurs in almost every county of Illinois (see Distribution Map). Habitats include moist black soil prairies, savannas and openings in woodlands, moist meadows near rivers, borders of lakes and edges of marshes, rocky bluffs, roadside ditches and low-lying areas along railroads, abandoned fields, vacant lots, and other waste areas. Moist disturbed areas are preferred.
Faunal Associations: The pollen or nectar of the flowers attract many kinds of insects, including long-tongued bees, short-tongued bees, wasps, flies, butterflies, skippers, beetles, and plant bugs. Examples of more frequent visitors include Little Carpenter bees, Nomadine Cuckoo bees, Green Metallic bees and other Halictine bees, Eumenine wasps, Tachinid flies, and Thick-Head flies. The caterpillars of Schinia lynx (Lynx Flower Moth) eat the flowers and seed capsules, while Lygus lineolaris (Tarnished Plant Bug) sucks the plant juices. Among mammalian herbivores, livestock, deer, and rabbits occasionally consume the leaves, stems, and flowers.
Photographic Location: The photographs were taken along a roadside ditch in Champaign, Illinois.
Comments: Philadelphia Fleabane can be distinguished from other fleabanes by the clasping leaves and the huge number of ray florets in a flowerhead. This plant is usually longer-lived and prefers moister locations than the other Fleabanes. Its floral display is also showier, but shorter-lived. Another common name for this plant is Marsh Fleabane. There is significant variation in the appearance of plants across different populations.